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Subject[tip:irq/core] genirq/affinity: Allow irq spreading from a given starting point
Commit-ID:  1a2d0914e23aab386f5d5acb689777e24151c2c8
Gitweb: https://git.kernel.org/tip/1a2d0914e23aab386f5d5acb689777e24151c2c8
Author: Ming Lei <ming.lei@redhat.com>
AuthorDate: Thu, 8 Mar 2018 18:53:57 +0800
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 6 Apr 2018 12:19:51 +0200

genirq/affinity: Allow irq spreading from a given starting point

To support two stage irq vector spreading, it's required to add a starting
point to the spreading function. No functional change, just preparatory
work for the actual two stage change.

[ tglx: Renamed variables, tidied up the code and massaged changelog ]

Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Link: https://lkml.kernel.org/r/20180308105358.1506-4-ming.lei@redhat.com

---
kernel/irq/affinity.c | 35 ++++++++++++++++++++---------------
1 file changed, 20 insertions(+), 15 deletions(-)

diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c
index a9c36904500c..213695a27ddb 100644
--- a/kernel/irq/affinity.c
+++ b/kernel/irq/affinity.c
@@ -94,17 +94,17 @@ static int get_nodes_in_cpumask(cpumask_var_t *node_to_cpumask,
return nodes;
}

-static int irq_build_affinity_masks(int nvecs, const struct irq_affinity *affd,
+static int irq_build_affinity_masks(const struct irq_affinity *affd,
+ int startvec, int numvecs,
cpumask_var_t *node_to_cpumask,
const struct cpumask *cpu_mask,
struct cpumask *nmsk,
struct cpumask *masks)
{
- int affv = nvecs - affd->pre_vectors - affd->post_vectors;
- int last_affv = affv + affd->pre_vectors;
- int curvec = affd->pre_vectors;
+ int n, nodes, cpus_per_vec, extra_vecs, done = 0;
+ int last_affv = affd->pre_vectors + numvecs;
+ int curvec = startvec;
nodemask_t nodemsk = NODE_MASK_NONE;
- int n, nodes, cpus_per_vec, extra_vecs;

nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);

@@ -112,12 +112,13 @@ static int irq_build_affinity_masks(int nvecs, const struct irq_affinity *affd,
* If the number of nodes in the mask is greater than or equal the
* number of vectors we just spread the vectors across the nodes.
*/
- if (affv <= nodes) {
+ if (numvecs <= nodes) {
for_each_node_mask(n, nodemsk) {
- cpumask_copy(masks + curvec,
- node_to_cpumask[n]);
- if (++curvec == last_affv)
+ cpumask_copy(masks + curvec, node_to_cpumask[n]);
+ if (++done == numvecs)
break;
+ if (++curvec == last_affv)
+ curvec = affd->pre_vectors;
}
goto out;
}
@@ -126,7 +127,7 @@ static int irq_build_affinity_masks(int nvecs, const struct irq_affinity *affd,
int ncpus, v, vecs_to_assign, vecs_per_node;

/* Spread the vectors per node */
- vecs_per_node = (affv - (curvec - affd->pre_vectors)) / nodes;
+ vecs_per_node = (numvecs - (curvec - affd->pre_vectors)) / nodes;

/* Get the cpus on this node which are in the mask */
cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
@@ -150,13 +151,16 @@ static int irq_build_affinity_masks(int nvecs, const struct irq_affinity *affd,
irq_spread_init_one(masks + curvec, nmsk, cpus_per_vec);
}

- if (curvec >= last_affv)
+ done += v;
+ if (done >= numvecs)
break;
+ if (curvec >= last_affv)
+ curvec = affd->pre_vectors;
--nodes;
}

out:
- return curvec - affd->pre_vectors;
+ return done;
}

/**
@@ -169,9 +173,9 @@ out:
struct cpumask *
irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
{
+ int curvec, affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
cpumask_var_t nmsk, *node_to_cpumask;
struct cpumask *masks = NULL;
- int curvec;

/*
* If there aren't any vectors left after applying the pre/post
@@ -198,8 +202,9 @@ irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
/* Stabilize the cpumasks */
get_online_cpus();
build_node_to_cpumask(node_to_cpumask);
- curvec += irq_build_affinity_masks(nvecs, affd, node_to_cpumask,
- cpu_possible_mask, nmsk, masks);
+ curvec += irq_build_affinity_masks(affd, curvec, affvecs,
+ node_to_cpumask, cpu_possible_mask,
+ nmsk, masks);
put_online_cpus();

/* Fill out vectors at the end that don't need affinity */
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